<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<script type="text/javascript">
			 var a="",
		        b="B有值";
		    var result=a||"A的值是假的",
		        result2=b||"B的值是假的";
		    console.log(result);
		    console.log(result2);
		</script>
	</body>
</html>
